KR102540645B1 - Light emitting device - Google Patents

Abstract

The light emitting device of the embodiment includes a substrate; and a plurality of light emitting cells disposed spaced apart from each other on the substrate, each of the plurality of light emitting cells comprising: a first conductivity type semiconductor layer disposed on the substrate; an active layer disposed on the first conductivity-type semiconductor layer; and a second conductivity-type semiconductor layer disposed on the active layer, wherein the first conductivity-type semiconductor layers of the adjacent light emitting cells are separated in a V-shaped groove.

Description

Light emitting device {LIGHT EMITTING DEVICE}

The embodiment relates to a light emitting device.

Light emitting devices such as light emitting diodes or laser diodes using group 3-5 or group 2-6 compound semiconductor materials of semiconductors are developed in thin film growth technology and device materials to produce various colors such as red, green, blue and ultraviolet. It is possible to implement white light with high efficiency by using fluorescent materials or combining colors, and compared to conventional light sources such as fluorescent and incandescent lights, low power consumption, semi-permanent lifespan, fast response speed, safety, and environmental friendliness are advantages. have

Therefore, a light emitting diode backlight that replaces the cold cathode fluorescence lamp (CCFL) constituting the backlight of the transmission module of the optical communication means, the backlight of the LCD (Liquid Crystal Display) display device, and the white light emitting diode that can replace the fluorescent lamp or incandescent lamp Applications are expanding to lighting devices, automobile headlights, and traffic lights, and with the expansion of these applications, a high-voltage light emitting device to which a plurality of light emitting cells is applied has recently been implemented.

1 is a cross-sectional view showing a conventional horizontal high voltage driving light emitting device 1 .

1, a conventional light emitting device may have a plurality of light emitting cells 20 disposed on a substrate 10, and each light emitting cell 20 includes a first conductivity type semiconductor layer 21, an active layer 22 and A first electrode pad 21a made of the second conductivity type semiconductor layer 23 and electrically connected to the first conductivity type semiconductor layer, a second electrode pad 23a disposed on the second conductivity type semiconductor layer, and It includes a passivation layer 40 that protects the light emitting cells and electrically separates the first electrode pad and the second electrode pad.

In the case of the conventional horizontal high-voltage driving light emitting device structure shown in FIG. 1, a photo process and an ICP dry etching process are performed in the process of separating sub chips to manufacture a light emitting device. There is a problem that the process is complex and takes a long time to manufacture.

The embodiment simplifies the manufacturing process of the light emitting device and improves light efficiency.

An embodiment is a substrate; and a plurality of light emitting cells disposed spaced apart from each other on the substrate, each of the plurality of light emitting cells comprising: a first conductivity type semiconductor layer disposed on the substrate; an active layer disposed on the first conductivity-type semiconductor layer; and a second conductivity type semiconductor layer disposed on the active layer, wherein the first conductivity type semiconductor layer of the adjacent light emitting cell is separated in the form of a V-shaped groove to provide a light emitting device.

For example, the upper end of the groove may have a width of 8 μm to 12 μm.

For example, the groove may be formed extending from the substrate.

For example, the top width of the groove formed in the substrate may be 4 μm to 6 μm.

For example, a first electrode pad disposed on the first conductivity-type semiconductor layer and a second electrode pad disposed on the second conductivity-type semiconductor layer may be further included.

For example, a passivation layer exposing the first electrode pad and the second electrode pad and disposed on the surface of the light emitting cell and the surface of the groove may be further included.

For example, the passivation layer may have a thickness of 550 nm to 650 nm.

For example, the passivation layer may be disposed on the surface of the groove with the same thickness.

For example, the passivation layer may fill the groove and have a flat upper surface.

For example, a connection electrode disposed on the passivation layer and connecting the first electrode pad of the light emitting cell and the second electrode pad of the neighboring light emitting cell may be further included.

The light emitting device according to the embodiment can greatly reduce the time and cost required to manufacture, thereby increasing productivity.

1 is a cross-sectional view showing a conventional horizontal high voltage driving light emitting device.
2 is a cross-sectional view showing a light emitting device according to an embodiment.
3 is a cross-sectional view showing another light emitting device according to another embodiment.
4A to 4F are diagrams illustrating a method of manufacturing a light emitting device according to an embodiment.
5A and 5B are views showing an active area of a conventional light emitting device and an active area of a light emitting device according to the present embodiment.

Hereinafter, examples will be described in order to explain the present invention in detail, and will be described in detail with reference to the accompanying drawings to help understanding of the present invention. However, embodiments according to the present invention can be modified in many different forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

In the description of the embodiment according to the present invention, in the case of being described as being formed on the "upper (above)" or "under (on or under)" of each element, the upper (upper) or lower (lower) (on or under) includes both elements formed by directly contacting each other or by indirectly placing one or more other elements between the two elements. In addition, when expressed as “up (up)” or “down (down) (on or under)”, it may include the meaning of not only the upward direction but also the downward direction based on one element.

In addition, relational terms such as "first" and "second", "upper/upper/upper" and "lower/lower/lower" used below refer to any physical or logical relationship or It may be used only to distinguish one entity or element from another, without necessarily requiring or implying an order.

In the drawings, the thickness or size of each layer is exaggerated, omitted, or schematically illustrated for convenience and clarity of explanation. Also, the size of each component does not entirely reflect the actual size.

2 is a cross-sectional view showing a light emitting device according to an embodiment.

The light emitting device 100 according to the embodiment may include a substrate 110, a plurality of light emitting cells 120, a groove 130, and a passivation layer 140.

In the light emitting device according to the embodiment, the substrate 110 may be formed of a material suitable for growing a semiconductor material, a carrier wafer, may be formed of a material having excellent thermal conductivity, and may include a conductive substrate or an insulating substrate. For example, the substrate may use at least one of sapphire (Al ₂ O ₃ ), SiC, Si, GaAs, GaN, ZnO, Si, GaP, InP, Ge, and Ga ₂ O ₃ . In addition, the substrate may be a sapphire substrate (PSS: Patterned Sapphire Substrate) having irregularities 115 processed on its surface in order to increase light extraction efficiency.

In the above embodiment, the plurality of light emitting cells 120 are arranged on the substrate 110, the plurality of light emitting cells is at least two, and a plurality of light emitting cells more than that can form a plurality of rows or columns. Each light emitting cell 120 may include a first conductivity type semiconductor layer 121 , an active layer 122 , and a second conductivity type semiconductor layer 123 .

The first conductivity-type semiconductor layer 121 may be formed of a semiconductor compound. It may be implemented as a compound semiconductor of group 3-5, group 2-6, etc., and may be doped with a first conductivity type dopant. When the first conductivity type semiconductor layer is an n-type semiconductor layer, the first conductivity type dopant is an n-type dopant and may include Si, Ge, Sn, Se, or Te, but is not limited thereto. The first conductivity-type semiconductor layer is a semiconductor having a composition formula of In _x Al _y Ga _(1-xy) N (0≤≤x≤≤1, 0≤≤y≤≤1, 0≤≤x+y≤≤1) may contain substances. The first conductivity-type semiconductor layer may be formed of one or more of GaN, InN, AlN, InGaN, AlGaN, InAlGaN, AlInN, AlGaAs, InGaAs, AlInGaAs, GaP, AlGaP, InGaP, AlInGaP, and InP.

In the active layer 122, electrons injected through the first conductivity-type semiconductor layer and holes injected through the second conductivity-type semiconductor layer meet each other to emit light having energy determined by an energy band specific to a material constituting the active layer. It is a layer. The active layer is at least one of a double hetero junction structure, a single quantum well structure, a multi quantum well (MQW) structure, a quantum-wire structure, or a quantum dot structure. can be formed For example, the active layer may be injected with trimethyl gallium gas (TMGa), ammonia gas (NH ₃ ), nitrogen gas (N ₂ ), and trimethyl indium gas (TMIn) to form a multi-quantum well structure, but is limited thereto It is not.

The well layer/barrier layer of the active layer may be, for example, one or more pairs of InGaN/GaN, InGaN/InGaN, GaN/AlGaN, InAlGaN/GaN, InAlGaN/InAlGaN, GaAs(InGaAs)/AlGaAs, and GaP(InGaP)/AlGaP. It may be formed into a structure, but is not limited thereto. The well layer may be formed of a material having a band gap lower than that of the barrier layer.

A conductive cladding layer (not shown) may be formed above or/and below the active layer. The conductive cladding layer may be formed of a semiconductor having a bandgap wider than that of the barrier layer or bandgap of the active layer. For example, the conductive cladding layer may include GaN, AlGaN, InAlGaN, or a superlattice structure. Also, the conductive cladding layer may be doped with n-type or p-type.

A second conductivity type semiconductor layer 123 is disposed on the active layer 122 . The second conductivity type semiconductor layer 123 may be formed of a semiconductor compound. It may be implemented as a compound semiconductor of group 3-5, group 2-6, etc., and may be doped with a second conductivity type dopant. For example, a semiconductor material having a composition formula of In _x Al _y Ga _{1 -xy} N (0≤≤x≤≤1, 0≤≤y≤1, 0≤≤x+y≤≤1) may be included. When the second conductivity type semiconductor layer 123 is a p-type semiconductor layer, the second conductivity type dopant is a p-type dopant and may include Mg, Zn, Ca, Sr, Ba, or the like.

A first electrode pad 121a may be disposed on the first conductivity-type semiconductor layer 121 , and a second electrode pad 123a may be disposed on the second conductivity-type semiconductor layer 123 .

The first electrode pad 121a may be an n-type ohmic electrode layer, and may include Al (Aluminum) or Ag (Silver) to serve as a reflective layer, and may include Al, Cr (Chrome)/Al, Ti (Titanium)/ It may be made of Al, Ag, or Ni (Nickel)/Ag.

The second electrode pad 123a may be formed of a light-transmissive conductive material and a metal material. For example, indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), or indium tin oxide (IAZO) may be used as the second electrode pad 123a. aluminum zinc oxide), IGZO (indium gallium zinc oxide), IGTO (indium gallium tin oxide), AZO (aluminum zinc oxide), ATO (antimony tin oxide), GZO (gallium zinc oxide), IZON (IZO Nitride), AGZO ( Al-Ga ZnO), IGZO (In-Ga ZnO), ZnO, IrOx, RuOx, NiO, RuOx/ITO, Ni/IrOx/Au, or Ni/IrOx/Au/ITO, Ag, Ni, Cr, Ti, Al , Rh, Pd, Ir, Sn, In, Ru, Mg, Zn, Pt, Au, may be formed including at least one of Hf.

In addition, the second electrode pad 123a may be composed of a p-type ohmic electrode layer and a reflective layer. The p-type ohmic electrode layer may be ITO (Indium Tin Oxide), ZnO, InO, SnO, or an alloy thereof, and the reflective layer may include Ag or Al, but is not limited to these materials.

When the plurality of light emitting cells 120 are disposed on the substrate 110, the adjacent light emitting cells 120 are adjacent to the grooves 130 formed between the first conductivity type semiconductor layers 121 of the neighboring light emitting cells 120. ) can be separated by

The groove 130 may be formed by irradiating a laser in a direction in which the light emitting cell 120 is mounted on the substrate 110, and may be formed in a shape in which a cross section becomes narrower toward the bottom. The groove 130 formed in the first conductivity-type semiconductor layer 121 may be formed to extend over the substrate 110 .

The top width W1 of the groove 130 formed in the first conductive semiconductor layer 121 may be 8 μm to 12 μm. A passivation layer 140 and a connection electrode 150, which will be described later, may be disposed on the surface of the groove 130. If the upper width W1 of the groove 130 is smaller than 8 μm, the passivation layer and the connection electrode will be disposed. Since the space is narrow, the passivation layer and the connection electrode cannot be disposed, and when the upper width W1 of the groove 130 is greater than 12 μm, the size of the light emitting device may unnecessarily increase.

Also, the top width W2 of the groove formed in the substrate 110 may be 4 μm to 6 μm. Since the height of the first conductivity type semiconductor layer 121 is low, the space may be narrow for the passivation layer and the connection electrode to be disposed in the groove formed in the first conductivity type semiconductor layer 121. By being formed extending to the groove, a space in which the passivation layer 140 can be disposed is secured so that the passivation layer 140 can be stably disposed in the groove.

A passivation layer 140 may be disposed on the surface of the light emitting cell 120 and the surface of the groove 130 so that the first electrode pad 121a and the second electrode pad 123a are exposed.

The passivation layer 140 serves to protect the light emitting cells 120, and electrically connects the first electrode pad 121a and the second electrode pad 123a between adjacent light emitting cells 120 or within one light emitting cell. It can be formed to separate.

The thickness T1 of the passivation layer 140 may be 550 nm to 650 nm. If the thickness T1 of the passivation layer 140 is smaller than 550 nm, cracks may occur in the passivation layer, and the thickness of the passivation layer 140 ( If T1) is thicker than 650 nm, a space in which a passivation layer and a connection electrode can be disposed between adjacent light emitting cells may be narrowed. However, the thickness of the passivation may vary depending on the size of the light emitting device or the shape of the groove.

As shown in Figure 2, The passivation layer 140 may be disposed on the surface of the groove 130 with the same thickness. That is, the passivation layer 140 disposed on the surface of the light emitting cell 120 or the surface of the groove 130 is disposed to have the same thickness, and when the connection electrode 150 is disposed on the passivation layer 140, the connection electrode ( 150) may also be arranged to fill the groove 130.

3 is a cross-sectional view showing another light emitting device according to another embodiment.

As shown in FIG. 3 , the passivation layer 140 may fill the groove 130 and have a flat upper surface. That is, the passivation layer 140 may fill the groove 130 and may be disposed in a plane such that an upper surface of the passivation layer 140 is parallel to the substrate 110 .

In addition, a connection electrode 150 may be disposed on the passivation layer 140 , and the connection electrode 150 is a second electrode of the light emitting cell 120 adjacent to the first electrode pad 121a of the light emitting cell 120 . The electrode pad 123a may be electrically connected.

The formed connection electrode 150 connects the first electrode pad 121a of one light emitting cell 120 among the two adjacent light emitting cells 120 and the second electrode pad 123a of the other light emitting cell 120. A plurality of light emitting cells 120 can be electrically connected in series by continuously connecting them, or one light emitting cell 120 and another light emitting cell 120 of two adjacent light emitting cells 120 have the same polarity. A plurality of light emitting cells 120 may be connected in parallel by connecting the electrodes of the light emitting cells 120 to each other.

The passivation layer 140 may be made of an inorganic film or a non-conductive oxide or nitride, and may be made of a material including any one of Si, N, Ti, and O, such as SiN, SiO ₂ , and TiO ₂ .

Each layer in the light emitting device according to the embodiment is formed by metal organic chemical vapor deposition (MOCVD), chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), or molecular beam growth. It may be formed using methods such as Molecular Beam Epitaxy (MBE) and Hydride Vapor Phase Epitaxy (HVPE), but is not limited thereto.

4A to 4F are diagrams illustrating a method of manufacturing a light emitting device according to an embodiment.

In FIG. 4A , the substrate 110 may be formed of a material suitable for growing a semiconductor material, a carrier wafer, may be formed of a material having excellent thermal conductivity, and may include a conductive substrate or an insulating substrate.

In FIG. 4B , irregularities 115 are formed on the upper surface of the substrate 110 on which the light emitting cell layer is to be formed in order to increase light extraction efficiency.

4C , a light emitting cell layer is formed by sequentially growing a first conductivity type semiconductor layer 121 , an active layer 122 , and a second conductivity type semiconductor layer 123 on a substrate 110 .

FIG. 4D shows that the first conductivity type semiconductor layer 121 of the neighboring light emitting cells 120 formed by being connected is irradiated with a laser to form a groove 130 in the upper portion of the first conductivity type semiconductor layer 121 and the substrate 110. By forming the adjacent light emitting cells 120 are separated.

4E shows the light emitting cell 120 so that the first electrode pad 121a disposed on the first conductivity type semiconductor layer 121 and the second electrode pad 123a disposed on the second conductivity type semiconductor layer 123 are exposed. A passivation layer 140 is disposed on the surface of the groove 130 and the surface of the groove 130 .

FIG. 4F shows a passivation layer so that the first electrode pad 121a of one light emitting cell 120 and the second electrode pad 123a of one light emitting cell 120 and the neighboring light emitting cell 120 are electrically connected. 140), the connection electrode 150 is disposed.

5A and 5B are views showing an active area of a conventional light emitting device and an active area of a light emitting device according to the present embodiment.

Referring to FIGS. 5A and 5B , in the case of the conventional light emitting device 1, the light emitting cells 20 are separated because the first conductivity type semiconductor layer is etched after a photo process is performed to separate the light emitting cells 20. ) of the active area (active area) was relatively reduced. However, in order to separate the light emitting cells 120, the light emitting device 100 according to the embodiment undergoes a process of forming grooves by irradiating a laser beam on the first conductivity type semiconductor layer of the light emitting cells 120, thereby emitting adjacent light. The light emitting cells 120 can be separated while maintaining a minimum distance between the first conductivity type semiconductor layers of the cells 120 .

As shown in FIGS. 5A and 5B, the active area of the light emitting device 100 according to the embodiment is increased by 16.67% compared to the active area of the conventional light emitting device 1, and thus the luminous efficiency of the light emitting device is 1.2%. increased.

Therefore, the light emitting device according to the embodiment can separate the light emitting cells 120 without significantly reducing the active area of the light emitting cells 120, and thus, the light emitting efficiency of the light emitting device can be greatly improved. there is.

In addition, in the case of the conventional horizontal high voltage driving light emitting device structure, a photo process and an ICP dry etching process are performed in the process of separating sub chips, which makes the light emitting device manufacturing process complicated. However, the light emitting device according to the embodiment can greatly reduce the time and cost required to manufacture, thereby increasing productivity.

The light emitting device according to the present embodiment is mounted on a submount to be applied to a light emitting device package in which the first electrode pad and the second electrode pad of the light emitting device can be electrically connected to the first and second bump portions of the submount. can

The submount may be implemented as a package body or a printed circuit board, and the submount may be polyphthalamide (PPA), liquid crystal polymer (LCP), or polyamide. Resin such as 9T (PolyAmide9T, PA9T), metal, photo sensitive glass, sapphire, ceramic, printed circuit board, and the like may be included. However, the submount according to the embodiment is not limited to these materials.

The first bump part and the second bump part are disposed between the submount and the light emitting element.

A plurality of light emitting device packages according to the embodiment may be arrayed on a substrate, and optical members such as a light guide plate, a prism sheet, a diffusion sheet, and the like may be disposed on a light path of the light emitting device package. The light emitting device package, substrate, and optical member may function as a backlight unit.

In addition, it may be implemented as a display device including a light emitting device package according to an embodiment, a pointing device, and a lighting device.

Here, the display device includes a bottom cover, a reflector disposed on the bottom cover, a light emitting module emitting light, a light guide plate disposed in front of the reflector and guiding light emitted from the light emitting module forward, and a light guiding plate disposed in front of the light guide plate. An optical sheet including prism sheets disposed thereon, a display panel disposed in front of the optical sheet, an image signal output circuit connected to the display panel and supplying image signals to the display panel, and a color filter disposed in front of the display panel. can include Here, the bottom cover, the reflector, the light emitting module, the light guide plate, and the optical sheet may form a backlight unit.

In addition, the lighting device includes a light source module including a substrate and a light emitting device package according to an embodiment, a radiator for dissipating heat from the light source module, and a power supply unit for processing or converting an electrical signal provided from the outside and providing it to the light source module. can include For example, the lighting device may include a lamp, a head lamp, or a street lamp.

The head lamp includes a light emitting module including light emitting device packages disposed on a substrate, a reflector that reflects light emitted from the light emitting module in a certain direction, for example, forward, and a lens that refracts the light reflected by the reflector forward. , and a shade that blocks or reflects a part of the light reflected by the reflector and directed to the lens to form a light distribution pattern desired by the designer.

Although the above has been described with reference to the embodiments, these are only examples and do not limit the present invention, and those skilled in the art to which the present invention belongs will not deviate from the essential characteristics of the present embodiment. It will be appreciated that various variations and applications are possible. For example, each component specifically shown in the embodiment can be modified and implemented. And differences related to these modifications and applications should be construed as being included in the scope of the present invention as defined in the appended claims.

100: light emitting element 120: light emitting cell
121: first conductivity type semiconductor layer 122: active layer
123: second conductivity type semiconductor layer 130: groove
140: passivation layer 150: connection electrode

Claims (10)

Board; and
It includes a plurality of light emitting cells disposed spaced apart from each other on the substrate,
Each of the plurality of light emitting cells,
a first conductivity type semiconductor layer disposed on the substrate;
an active layer disposed on the first conductivity-type semiconductor layer; and
A second conductivity-type semiconductor layer disposed on the active layer; includes,
V-shaped groove; a passivation layer disposed on a surface of the light emitting cell and a surface of the V-shaped groove; And a connection electrode disposed on the passivation layer and electrically connected to a neighboring light emitting cell; further comprising,
The first conductivity-type semiconductor layer of the neighboring light emitting cell is separated in the form of the V-shaped groove extending from the substrate,
At least a portion of the connection electrode is disposed in the V-shaped groove. According to claim 1,
The passivation layer is disposed on the surface of the V-shaped groove with a uniform thickness,
A thickness of the passivation layer is 550 nm to 650 nm, a light emitting device. According to claim 1,
Further comprising a first electrode pad disposed on the first conductivity-type semiconductor layer and a second electrode pad disposed on the second conductivity-type semiconductor layer,
The passivation layer exposes the first electrode pad and the second electrode pad. According to claim 1,
The width of the upper end of the V-shaped groove formed in the first conductive semiconductor layer is 8 μm to 12 μm,
The width of the upper end of the V-shaped groove formed on the substrate is 4㎛ to 6㎛, the light emitting device. According to claim 1,
Further comprising a first electrode pad disposed on the first conductivity-type semiconductor layer and a second electrode pad disposed on the second conductivity-type semiconductor layer,
The connection electrode connects the first electrode pad of the light emitting cell and the second electrode pad of the neighboring light emitting cell. delete delete delete delete delete

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